Subsea electric installations, such as transformers or frequency converters, are assemblies used under water. Installations, such as transformers, can include a vessel filled with insulation and/or cooling fluid to encounter for the high pressure due to deep water depth. During operation of the installation, temperature and volume of the insulation and/or cooling fluid varies, whereby pressure compensation of the fluid is used. This involves use of a pressure compensator, which is in fluid connection with the vessel of the installation. The pressure compensator receives excess fluid when its temperature and volume increase, and returns the fluid back to the vessel when it cools down.
Leakage of seawater into the pressure compensator and/or the installation is a serious risk as it may prevent the operation of the installation or damage the installation. Improved arrangements are also needed to prevent such leakage, and minimize disadvantages if such a leakage occurs.